Starbucks Is Getting Rid of Plastic Straws for the Environment. But Sippy Cups Are Worse for Our Teeth.

Starbucks, America’s favorite coffee chain and purveyor of hip acoustic soundtracks, announced on Monday that it plans to take its hometown of Seattle’s recent ban on plastic straws one step further. By 2020, every single one of the company’s 28,000 stores worldwide will phase out plastic straws by replacing their current lids with a strawless version that some have described as “adult sippy cups.” If you’ve ordered a nitro cold brew in recent months, the new lids will look familiar; but if you haven’t yet had the pleasure, the company describes the lids as featuring “a teardrop-shaped opening about the size of a thumbprint—a cleaner, less-ridged version of a hot cup lid.” The lids were initially designed to allow customers to “exult in the frothy foam,” which the Starbucks engineer calls “the hero of Nitro coffee,” and unlike straws, are recyclable. Within the next year and a half, the sippy cup will be standard for all iced drinks except Frappuccinos.

Starbucks estimates that the move will eliminate more than 1 billion straws a year. Plastic straw bans have recently gained traction in cities like Seattle and with companies like Starbucks and McDonalds, which announced that they’ll be phasing them out at restaurants in the U.K. and Ireland. The move is one that is undoubtedly beneficial for the environment—a study from earlier this year estimated that as many as 8.3 billion plastic straws end up polluting the world’s beaches. But while Starbucks’ recent announcement might’ve made environmental advocates jump for joy, it struck fear into the heart of anyone convinced that straws are the only thing standing in between their pearly whites and the notorious staining power of their daily Americano.

According to Harvard-trained dentist and Slate contributor Nisarg A. Patel, that fear isn’t entirely unfounded. “If you had to choose between drinking from a straw and drinking from a sippy cup, it’s more likely that the tooth will be exposed to more acid and sugar [through the latter] than it would through a straw,” he said. “There’s a higher risk for damage.” And that damage isn’t just aesthetic. Acidic foods and drinks with high sugar contents (i.e., almost everything on the Starbucks menu) not only create a favorable environment for tooth-decaying bacteria but can also degrade tooth enamel, which can lead to increased sensitivity and decay.

Patel cited a 1998 study in the British Dental Journal that compared drinking from a cup with drinking through a straw, using video cameras to “see what volume of liquid was hitting the surface of teeth. They found that straws were more effective than drinking from a cup in reducing the amount of surface area that was exposed to those liquids.” Although he stipulated that the study had a small sample size, he still recommends that his patients who are concerned about tooth staining or cavities use a straw when drinking acidic, sugary drinks. For those who are both environmentally and dentally conscious, Patel advised drinking a few glasses of water after your daily cup of coffee to help wash out the sugar and partly neutralize some of acidity. Even better: start carrying mouthwash. But he suggested holding off on brushing your teeth immediately: “It’s a topic of debate, but some dentists say that if you expose your mouth to an acidic environment, it softens the enamel. If you then put hard bristles on it by brushing immediately afterwards that can worsen the problem.”

If you don’t want to take any of those precautions, Starbucks is currently testing out eco-friendly straws made out of either paper or compostable plastic, so you can still enjoy your daily iced soy no-whip, no-foam macchiato with reduced dental damage—for now.